1. Field of the Invention
The present invention relates to a gas sensor which connects with an external electric device, i.e. ECU (Electronic Control Unit), through a single output system. Also, the present invention relates to an output processing method to be performed on the gas sensor.
2. Description of Relevant Art
Generally, in a fuel cell which adopts solid polymer electrolyte membrane, a fuel cell stack is configured by stacking a plurality of single cells; each single cell is obtained by sandwiching a solid polymer electrolyte membrane by a fuel electrode and an oxygen electrode.
In this fuel cell, hydrogen is supplied, as fuel, to the fuel electrode and air is supplied, as oxidant, to the oxygen electrode. Then, hydrogen ion caused by a catalytic reaction at the fuel electrode passes through the solid polymer electrolyte membrane and reaches to the oxygen electrode. Thus, electric power is generated through an electrochemical reaction between hydrogen ion and oxygen.
In this kind of fuel cell adopting a solid polymer membrane, conventionally, a gas sensor is provided at an exhaust line of oxygen electrode-side, and a technique, which detects the leakage into the oxygen electrode side of hydrogen through the solid polymer membrane from the fuel electrode side using this sensor, has been discovered (see Japanese unexamined patent publication No. 2004-61244).
In the gas sensor disclosed in this Japanese unexamined patent publication, the gas sensor connects with ECU using two output systems, and supplies the outputs to ECU using two output systems. Here, one of outputs is the output based on a hydrogen concentration and the other of output is the output based on the error of the gas detector.
Therefore, the gas sensor, which connects with an external electric device through a single system and which can supply, by using this single system, the output which is determined based on a target gas and the output which is determined based on the error of the gas detector installed in the gas sensor, has been required.